In geology, a boulder is a rock fragment with size greater than 25.6 centimetres (10.1 in) in diameter. Smaller pieces are called cobbles and pebbles. While a boulder may be small enough to move or roll manually, others are extremely massive. In common usage, a boulder is too large for a person to move. Smaller boulders are usually just called rocks or stones. The word boulder derives from boulder stone, from the Middle English bulderston or Swedish bullersten.
Karlu Karlu / Devils Marbles Conservation Reserve is a protected area in the Northern Territory of Australia located in the locality of Warumungu about 105 km (65 mi) south of Tennant Creek, and 393 km (244 mi) north of Alice Springs. The nearest settlement is the small town of Wauchope located 9 km (5.6 mi) to the south.
The exposed geology of the Yosemite area includes primarily granitic rocks with some older metamorphic rock. The first rocks were laid down in Precambrian times, when the area around Yosemite National Park was on the edge of a very young North American continent. The sediment that formed the area first settled in the waters of a shallow sea, and compressive forces from a subduction zone in the mid-Paleozoic fused the seabed rocks and sediments, appending them to the continent. Heat generated from the subduction created island arcs of volcanoes that were also thrust into the area of the park. In time, the igneous and sedimentary rocks of the area were later heavily metamorphosed.
A hoodoo is a tall, thin spire of rock formed by erosion. Hoodoos typically consist of relatively soft rock topped by harder, less easily eroded stone that protects each column from the elements. They generally form within sedimentary rock and volcanic rock formations.
Grand Coulee is an ancient river bed in the U.S. state of Washington. This National Natural Landmark stretches for about 60 miles (100 km) southwest from Grand Coulee Dam to Soap Lake, being bisected by Dry Falls into the Upper and Lower Grand Coulee.
A glacial erratic is a glacially deposited rock differing from the type of rock native to the area in which it rests. Erratics, which take their name from the Latin word errare, are carried by glacial ice, often over distances of hundreds of kilometres. Erratics can range in size from pebbles to large boulders such as Big Rock in Alberta.
The exposed geology of the Death Valley area presents a diverse and complex set of at least 23 formations of sedimentary units, two major gaps in the geologic record called unconformities, and at least one distinct set of related formations geologists call a group. The oldest rocks in the area that now includes Death Valley National Park are extensively metamorphosed by intense heat and pressure and are at least 1700 million years old. These rocks were intruded by a mass of granite 1400 Ma and later uplifted and exposed to nearly 500 million years of erosion.
A mushroom rock, also called rock pedestal, or a pedestal rock, is a naturally occurring rock whose shape, as its name implies, resembles a mushroom. The rocks are deformed in a number of different ways: by erosion and weathering, glacial action, or from a sudden disturbance. Mushroom rocks are related to, but different from, yardang.
Rock balancing is a form of recreation or artistic expression in which rocks are piled in balanced stacks, often in a precarious manner.
Rocking stones are large stones that are so finely balanced that the application of just a small force causes them to rock. Typically, rocking stones are residual corestones formed initially by spheroidal weathering and have later been exposed by erosion or glacial erratics left by retreating glaciers. Natural rocking stones are found throughout the world. A few rocking stones might be man-made megaliths.
There are many large stones of Scotland of cultural and historical interest, such as the distinctive Pictish stones.
Tripod Rock is a glacial erratic, in this specific case a balancing rock, or perched boulder, located in Kinnelon, New Jersey in the Pyramid Mountain Natural Historic Area. This multi-ton Precambrian gneiss boulder, located near the edge of a long ridge, is balanced on three smaller boulders. Tripod Rock is roughly 6 m (20 ft) long, 3 m (9.8 ft) wide, and 2.5 m high, weighing approximately 127 tonnes (280,000 lb). A triangular crest runs the length of its top. The boulder is balanced on three smaller stones roughly 1 m in diameter that raise it above the bedrock by about 0.5 m at its lowest point. The point of contact between the boulder and its support stones forms an approximate 3-4-5 triangle.
The Monoliths, formerly known as Agassiz Rock, is a 116-acre (47 ha) park in Manchester-by-the-Sea, Massachusetts, owned and maintained by The Trustees of Reservations. The park's name is from two examples of large glacial erratic boulders plucked from bedrock. As glaciers scoured this landscape, the mass of bedrock forming the hill proved more resistant than the surrounding soil, forcing the bottom of the glacier up and over the hill. The north side was smoothed and the south side left steep and rugged as the glacier broke off chunks of rock as it passed.
The Fountain Formation is a Pennsylvanian bedrock unit consisting primarily of conglomerate, sandstone, or arkose, in the states of Colorado and Wyoming in the United States, along the east side of the Front Range of the Rocky Mountains, and along the west edge of the Denver Basin.
Mama Bhagne Paharh is a rock formation near Dubrajpur town of Birbhum district in the Indian state of West Bengal.
Okanagan Falls is a community located on the south end of Skaha Lake in British Columbia.
Boulder Park National Natural Landmark, of Douglas County, Washington, along with the nearby McNeil Canyon Haystack Rocks and Sims Corner Eskers and Kames natural landmarks, illustrate well-preserved examples of classic Pleistocene ice stagnation landforms that are found in Washington. These landforms include numerous glacial erratics and haystack rocks that occur near and on the Withrow Moraine, which is the terminal moraine of the Okanogan ice lobe.
Cape Town lies at the south-western corner of the continent of Africa. It is bounded to the south and west by the Atlantic Ocean, and to the north and east by various other municipalities in the Western Cape province of South Africa.
